A bacterial flora in the oral cavity is constituted by 400 to 500 kinds of microorganisms. Therefore, various pathogenic microorganisms such as cariogenic bacteria, periodontal disease bacteria and candida bacteria are present in the oral cavity, which causes various diseases such as dental caries, periodontal diseases, glossitis, thrush and oral candidiasis. Furthermore, it is reported in recent studies that candida bacteria also relate to periodontal diseases.
Therefore, many suggestions have been heretofore made with respect to oral compositions containing an antibacterial substance. However, even an antibacterial agent was administered to the oral cavity, the antibacterial agent was washed out by saliva or a food or beverage within a short time, and thus the effect thereof had to be said to be a transient effect.
Furthermore, in view of that a lactic acid bacterium suppresses bacteria causing various diseases in the large intestine, studies for applying the technique thereof to dental diseases have been done. For example, it was reported that lactic acid bacteria such as Lactobacillus salivarius (Patent Document 1 and Patent Document 2), Lactobacillus reuteri (Patent Document 3 and Patent Document 4), Lactobacillus paracasei (Patent Document 5), Lactobacillus delbrueckii (Patent Document 6) and Lactobacillus fermentum (Non-patent Document 1) are effective for the prophylaxis of dental caries and periodontal diseases.
However, there was also a problem that even a lactic acid bacterium having an antibacterial effect against cariogenic bacteria and periodontal disease bacteria has a narrow antibacterial spectrum, has insufficient fermentability and thus cannot provide a good fermented product, and cannot provide a fermented product having good flavor and being excellent in palatability.